Alright guys, I'm on my third cluster now.... First one had a bad tach, replaced it and eventually the speedo motor went on the second one. Now I have a nice pricey 145mph cluster, and once again the tach is off! I tried replacing only the tachs(took the good one out of the old cluster w/ broken speedo), and no luck, which leads me to believe the electronics in the actual cluster are screwed.
So I'm looking at trieing to wire the stock tach directly to the MSD box, and was wondering if anyone could point me in the right direction. Thank you in advance

 

First thing, remove your factory tach filter (if you haven't already done so). To make my 6AL box work with the factory tach in my 140 mph cluster I had to purchase the MSD tach adapter #8920. They have another tach adapter that is supposed to be used under different circumstances (#8910), but this one didn't work for me. I have a MSD billet distributor and using the magnetic pick-up wires to trigger the 6AL box (I believe this is what makes the difference in which tach adapter to use). You might want to give MSD's tech line a call just to be certain which one you need: 915-855-7123.

MSD #8920
MSD #8910

MCM

 

I'm using a MSD 6AL box on a factory console no problems. I tried hooking up the tach wire to the tach output on the box but the car would crank and no start that way... guessing I didn't bypass something along the line right. I just took the factory filtor off and it's working fine... once and awhile it will act up (drop to 0 during WOT), but that's not common occurance. Like 1 or twice every 4 or 5 months if that.

 

Thank you for the help guys. Now for a stupid question.....where is the tach filter exactly? I can just remove it I take it?

 

That's exactly what mine did, but as soon as the needle hit a certain rpm (it was either 5 or 6 grand), it would drop to 0 every time. The MSD #8920 fixed this. I even had my factory tach checked for accuracy and it was amazingly accurate, except for being about 200 rpm off at about 7,000 rpm.

MCM

 

Well, I guess tbi's didn't come with tach filters, or at least not my year. I checked behind the distributor for it, as Tim described in another post, and nothing.

So can anyone point me to the correct wire to splice into to wire up the MSD directly? I would preffer it to be only the tach wire, and not the wire going to the ecm. Winaldl shows that my ecm is getting the correct engine speed, and I definetely doen't want to mess that up. Thank you
Roy